Food service carts in airplanes arc often used to store liquor and other valuable items. In some instances, expensive cameras, watches and jewelry are stored for duty free sale during international flights. Theft of items locked away in food service carts is not uncommon and results in substantial monetary loss to vendors of these products.
Of greater potential consequence is the ease with which even padlocked carts can be broken into which raises serious concerns for security personnel and for the public at large. It is all too conceivable that weapons, bombs or terrorist contraband could be smuggled aboard an airplane in a food service cart.
Another concern is that the serving attendant must bend down repeatedly to retrieve trays or to replace trays when food is being served. When an airplane flies through stretches of turbulent or "bumpy" air, the service attendant may find it necessary to open and close a door on the service cart many times in a single tour through the aisles of the vehicle. A more ergonomically considered door latch would lessen the bending required of service attendants and thereby reduce fatigue and the possible occurrence of repetitive stress injuries.
Conventional food service carts for airplanes generally have slidable door latches located at a point midway along the vertical height of the doors. A latch is recessed into each door and can be slid horizontally into a catch located in the side frame of the cart.
In addition, a hasp and staple are usually provided which enables the cart doors to be padlocked. The staple is attached to the door frame or to an extension of a food tray support rail. When the door is closed the staple protrudes through the hasp which is located approximately one third of the way down the vertical height of the door. The hole in the staple is designed to accept the shackle of a small padlock. The hasp is recessed so that the staple and padlock will not project beyond the front of the cart. This reduces the likelihood that passers-by or their clothing will become ensnared by either the staple or padlock. Neither the shackle of the padlock nor the metal of the staple is particularly thick in cross-section as a consequence of the need for compactness and the concern for saving weight characteristic of equipment used aboard aircraft. In cases reported by airline carriers and by vendors of goods which were lost due to thievery, the sheet metal staple was cut and bent away enabling the removal of the small padlock. In some instances the goods were removed and the padlock was returned to its original position. Then the metal staple was bent back into place which disguised evidence of intrusion and delayed discovery of the theft.
Many devices exist to improve the effectiveness of door latching mechanisms including the development in a related art of more effective hasps for padlocks. An early British patent No. 6113 (1911) to Vaughan shows angle plates mounted on a window sash which act as hasps for a padlock. Each angle plate is hinged to a mounting plate in a manner designed to cover up the mounting screws and thus hinder unauthorized removal of the hasp. A hasp may be regarded as any device used for mating doors, or a door and its accompanying structure, which has an aperture for the acceptance of the shackle of a padlock. Door hasps having offset matable plates, one mounted on the door edge and one mounted on the door jamb is taught by Clarke, U.S. Pat. No. 2,845,295 (1958).
In Nikola, U.S. Pat. No. 3,460,861 (1969), a pair of staples is shown in which one has a flange around part of the edge of its outwardly projecting side. The second staple, when held adjacent to the first staple, will fit snugly against it within the protective flange. This makes it more difficult to damage the shackle of a padlock holding the pair of staples together.
More recently, U.S. Pat. No. 4,745,783 (1988) to Poe discloses padlock hasps more resistant to tampering incorporating guard plates which limit access to the padlock shackle by common bolt cutters, hacksaws arid the like. Similarly, patents issued to Anderson, U.S. Pat. No. 4,949,560 (1990) and U.S. Pat. No. 4,961,329 (1990) present padlock hasps with protective mounting plates to suit a variety of common padlocks with different length shackles. In a patent issued to Wilson, U.S. Pat. No. 3,665,736 (1972), a locking bar is shown which can be extended to surround the front of a cabinet. At one location on the bar, adjacent flanges meet as hasps which can accept the shackle of a padlock and thereby prevent unauthorized access to a vending machine. The Wilson device is intended to act as a second high security lock for a cabinet which is opened infrequently. In design and massiveness it differs markedly from the instant invention which requires compactness and ease of entry.
While many devices in this related art exist to protect padlock shackles and cabinet entry, none is particularly appropriate for use on food service carts in airplanes where quick and frequent access to the storage compartment is required.